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E-7 Sheepdog (ret)
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This was brought up in another thread, and, to avoid a hijack, I started this one.

Oddly enough, hanging around performance boating boards for 5 years now, I had never heard of this mod.

Drilling a small hole in a front oil gallery plug (or 2 plugs) to directly spray more oil on the timing setup than it recieves from normal bleed off the front cam and crank bearings.
Very interesting idea.

Is there any sort of a "trigger point" where this becomes a good idea?

Is it just "one of those ideas" that's been arround a long time?

Great deal of validity to it, some, virtually no use, etc.......................????

Compared to many on here, I run a rather mild engine, but, it's pretty aggressive for what it is, a hydraulic cammed Mk-IV 454 in my heavy old cruiser Taylor SS to just short of 6-grand against an Aggressor B impeller.
The Comp double-roller torrington-bearinged timing chain is holding op nicely, with zero oiling mods, '04 was it's first year.

Discussion of this mod...............................................................
 

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The whole idea of drilling the 2 plugs behind the t gears on a BBC got its start because it helped eliminate noisey hyd lifters on start up, due to an air lock on the end of the galley. It wasn't for oiling the chain, the chain gets way, way more oil than it can ever use, or need. Some drill a hole behind the cam gear, in the thrust area, that intersects the galley between the #1 main and the #1 cam bearing. It helps to lube the back of the cam gear and reduce wear on the block. Personally, I perfer to just use a torrington.



 

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A timing chain oiler bleed is typically not needed unless you are running roller cam bearings. As GN said, it gets more than enough from main and cam bearing bleed.
About the only time bleeds (oilers) are used on a plain bearing engine is when using a belt drive. With a front and rear thrust washer assy used in most belt drives oil can have a tough time reaching the front washer. A little work on the belt drive plate helps too, but we're really getting off track now!
 

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I'm baaaaack...
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It's been a SBC trick for decades as well. Drill out the plugs 0.030" to spray on the chain (as a side effect, not the main reason) so that the air isn't trapped in the lifter gallery. I remember seeing this trick in a book by or about Grumpy Jenkins when it was no longer secret. I have no real idea if there was research on or long-term effects shown by the mod.

I'd use aluminum plugs for two reasons - easier to drill (0.030" drills are fragile), and less weight.
 

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21 Daytona
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Now that is very interesting. Why would the factory drill a hole in the main galley plug?
Not sure, if you read pic #8 these supply controlled engine oil to the timing chain.

this is exactly how mine was when I disassembled it and how Sunset put it back when they built the short block.
it was a hydraulic roller HO 502 originally.

It could be for the gen 6 style cam retainer plate
 

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A timing chain oiler bleed is typically not needed unless you are running roller cam bearings. As GN said, it gets more than enough from main and cam bearing bleed.
About the only time bleeds (oilers) are used on a plain bearing engine is when using a belt drive. With a front and rear thrust washer assy used in most belt drives oil can have a tough time reaching the front washer. A little work on the belt drive plate helps too, but we're really getting off track now!
No NO No, not off track at all warp, I belive title said oil bleeds for timming set? didn't say chain or belt ;) Please explain the mod for a belt drive as I'm installing a jesel belt drive on my bbc this time around.

thanks Don
 

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steelcomp was here
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No NO No, not off track at all warp, I belive title said oil bleeds for timming set? didn't say chain or belt ;) Please explain the mod for a belt drive as I'm installing a jesel belt drive on my bbc this time around.

thanks Don
"That'll be $500.00 sent to...." ;)
:D

I think every four bolt main BB Chev I've ever taken apart has had a drilled plug.
 
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A timing chain oiler bleed is typically not needed unless you are running roller cam bearings. As GN said, it gets more than enough from main and cam bearing bleed.
About the only time bleeds (oilers) are used on a plain bearing engine is when using a belt drive. With a front and rear thrust washer assy used in most belt drives oil can have a tough time reaching the front washer. A little work on the belt drive plate helps too, but we're really getting off track now!
I too am installing a Jesel and would like to hear more on this.

Tim
 

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I will be at the shop later this afternoon and will take a couple of pics of a modified Jessel cover. It's pretty easy to do with a die grinder or dremel and greatly helps the life of the thrust washers/needle bearings depending on which type you have.

On that GenVI deal, I can see them needing it due to the retainer plate blocking oil flow. I imagine they went to the plate due to a hydraulic roller?
 

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steelcomp was here
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Were those all factory engines, first time apart?
As far as I know. One was a Harman Marine. The Gen 6 I'm doing has one as well, and I'm glad I cought it...I didn't take the plugs out of this enigne so I never saw it originally. I already had the cam in and ready to button up the botom end and as I was installing a couple of other plugs I noticed one had a hole in it! That would have been a mess!:)sphss
 

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steelcomp was here
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I will be at the shop later this afternoon and will take a couple of pics of a modified Jessel cover. It's pretty easy to do with a die grinder or dremel and greatly helps the life of the thrust washers/needle bearings depending on which type you have.

On that GenVI deal, I can see them needing it due to the retainer plate blocking oil flow. I imagine they went to the plate due to a hydraulic roller?
They went to the plate to finally be as smart as Ford.:D:)devil
 

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I thought the plate had a tapering groove already cut in it on the cam side to oil the thrust surface.

I had never put together a BBC and bought a book on the gen 5-6 series. (I have a 5 )It was info I wanted to error on the safe side so I put it back how it came apart.
 
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